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2 years ago

If x = 6 and y = -4, evaluate 3x2 - 5y

Mathematics

2 answers:

guajiro [1.7K]2 years ago

8 0

Answer:

the answer is 56

Step-by-step explanation:

3×6×2= 36 and 5×-4=-20. 36-(-20) is 56

Elza [17]2 years ago

3 0

Answer:

solution = 128

Step-by-step explanation:

if x = 6 , y = -4

then,

( 3 × 6 × 6 ) - ( 5 × -4 )
108 + 20
128

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I need help on this question

egoroff_w [7]

25 is the answer hope it helped

8 0

3 years ago

Find the area of a triangle bounded by the y-axis, the line f(x)=9−4/7x, and the line perpendicular to f(x) that passes through

Setler79 [48]

<u>ANSWER: </u>

The area of the triangle bounded by the y-axis is $\frac{7938}{4225} \sqrt{65} \text { unit }^{2}$

<u>SOLUTION:</u>

Given, $f(x)=9-\frac{-4}{7} x$

Consider f(x) = y. Hence we get

$f(x)=9-\frac{-4}{7} x$ --- eqn 1

$y=9-\frac{4}{7} x$

On rewriting the terms we get

4x + 7y – 63 = 0

As the triangle is bounded by two perpendicular lines, it is an right angle triangle with y-axis as hypotenuse.

Area of right angle triangle = $\frac{1}{ab}$ where a, b are lengths of sides other than hypotenuse.

So, we need find length of f(x) and its perpendicular line.

First let us find perpendicular line equation.

Slope of f(x) = $\frac{-x \text { coefficient }}{y \text { coefficient }}=\frac{-4}{7}$

So, slope of perpendicular line = $\frac{-1}{\text {slope of } f(x)}=\frac{7}{4}$

Perpendicular line is passing through origin(0,0).So by using point slope formula,

$y-y_{1}=m\left(x-x_{1}\right)$

Where m is the slope and $\left(\mathrm{x}_{1}, \mathrm{y}_{1}\right)$

$y-0=\frac{7}{4}(x-0)$

$y=\frac{7}{4} x$ --- eqn 2

4y = 7x

7x – 4y = 0

now, let us find the vertices of triangle, one of them is origin, second one is point of intersection of y-axis and f(x)

for points on y-axis x will be zero, to get y value, put x =0 int f(x)

0 + 7y – 63 = 0

7y = 63

y = 9

Hence, the point of intersection is (0, 9)

Third vertex is point of intersection of f(x) and its perpendicular line.

So, solve (1) and (2)

$\begin{array}{l}{9-\frac{4}{7} x=\frac{7}{4} x} \\\\ {9 \times 4-\frac{4 \times 4}{7} x=7 x} \\\\ {36 \times 7-16 x=7 \times 7 x} \\\\ {252-16 x=49 x} \\\\ {49 x+16 x=252} \\\\ {65 x=252} \\\\ {x=\frac{252}{65}}\end{array}$

Put x value in (2)

$\begin{array}{l}{y=\frac{7}{4} \times \frac{252}{65}} \\\\ {y=\frac{441}{65}}\end{array}$

So, the point of intersection is $\left(\frac{252}{65}, \frac{441}{65}\right)$

Length of f(x) is distance between $\left(\frac{252}{65}, \frac{441}{65}\right)$ and (0,9)

$\begin{aligned} \text { Length } &=\sqrt{\left(0-\frac{252}{65}\right)^{2}+\left(9-\frac{441}{65}\right)^{2}} \\ &=\sqrt{\left(\frac{252}{65}\right)^{2}+0} \\ &=\frac{252}{65} \end{aligned}$

Now, length of perpendicular of f(x) is distance between $\left(\frac{252}{65}, \frac{441}{65}\right) \text { and }(0,0)$

$\begin{aligned} \text { Length } &=\sqrt{\left(0-\frac{252}{65}\right)^{2}+\left(0-\frac{441}{65}\right)^{2}} \\ &=\sqrt{\left(\frac{252}{65}\right)^{2}+\left(\frac{441}{65}\right)^{2}} \\ &=\frac{\sqrt{(12 \times 21)^{2}+(21 \times 21)^{2}}}{65} \\ &=\frac{63}{65} \sqrt{65} \end{aligned}$

Now, area of right angle triangle = $\frac{1}{2} \times \frac{252}{65} \times \frac{63}{65} \sqrt{65}$

$=\frac{7938}{4225} \sqrt{65} \text { unit }^{2}$

Hence, the area of the triangle is $\frac{7938}{4225} \sqrt{65} \text { unit }^{2}$

8 0

3 years ago

The amount of sales tax on a new car is directly proportional to the purchase price of the car. Victor bought a new car for $30,

Airida [17]

Answer:

Rita paid 47,500 dollars for the purchase price.

Step-by-step explanation:

We are given the sales tax on a new car is directly proportional to the purchase price of the car which means there is is something k such that

when you multiply it to the sales tax you get the purchase price.

Let's set this equation:

y=kx

Let y represent the purchase price and x the sales tax.

The second sentence tells us that (x,y)=(1500,30000).

We can plug this into y=kx to find the constant k. (Constant means it stays the same no matter what the input and output is).

So we have:

30000=k(1500)

300 =k(15) I went ahead and divided previous equation by 100.

Now divide both sides by 15:

300/15=k

Simplify:

20=k

So the equation to use the answer the question is

y=20x

where y is purchase price and x is sales tax.

So we want to know the purchase price on a car if the sales tax is 2375.

So replace x with 2375:

y=20(2375)

y=47500

3 0

2 years ago

Read 2 more answers

X-8 mathematics expression

kakasveta [241]

In order to solve this i'd have to know what x equals?? does it tell you?

3 0

2 years ago

What is a triangle with at least two congruent sides called?

PilotLPTM [1.2K]

Isosceles triangle I think

3 0

2 years ago